Refrigerating apparatus with defrost means



Oct. 9, 1962 J. w. JACOBS 3,057,159

REFRIGERATING APPARATUS WITH DEFROSTMEANS Filed March 24, 1961 I l l INVENTOR.

James M Jacobs United States Patent Office 3,057,159 Patented Oct. 9,1962 3,057,169 REFRIGERATIN G APPARATUS WITH DEFROST MEANS James W.Jacobs, Dayton, Ohio, assignor to General Motors Corporation, Detroit,Mich, a corporation of Delaware Filed Mar. 24, 1961, Ser. No. 98,162 12Claims. (Cl. 62-154) This invention relates to refrigerating apparatusand more particularly to an improved refrigerant circuit and an improvedcontrol for the circuit.

It is an object of this invention to provide an improved refrigerantcircuit wherein it is only necessary to make one opening into therefrigerant condenser.

Another object of this invention is to provide an improved arrangementfor defrosting a refrigerant evaporator.

More particularly, it is an object of this invention to provide animproved type of magnetically operated valve arrangement fordisconnecting the liquid line from the evaporator and for supplyingrelatively hot refrigerant from the condenser to the evaporator fordefrosting the evaporator.

Still another object of this invention is to provide an improvedrefrigerating system wherein a capillary tube type of restrictor has itsoutlet end arranged to be movable into and out of direct fluid flowrelationship with the inlet of the evaporator.

These and further objects and advantages of the present invention willbe apparent from the following description, reference being had to theaccompanying drawing wherein a preferred embodiment of the presentinvention is clearly shown.

In the drawing:

FIGURE 1 is a schematic view showing the refrigerant circuit and theelectrical controls for the same.

FIGURE 2 is a fragmentary sectional view on an enlarged scale showingthe control for the outlet of the capillary tube restrictor.

FIGURE 3 is a sectional view taken substantially on line 3-3 of FIGURE2.

Referring now to the drawing wherein a preferred embodiment of theinvention has been shown, the refrigerating system includes aconventional motor compressor unit it a condenser 12, a receiver 14, acapillary tube type restrictor 16 for supplying liquid refrigerant fromthe receiver 14 to the evaporator 18 located in a food storagecompartment 40. The vaporized refrigerant leaving the evaporator 18 iscompressed by the compressor 18 in the usual manner and the refrigerantthus compressed fiows through an outlet line 21) which joins with theline 22 leading from the condenser 12 to the evaporator 18.

During normal operation of the refrigerating system, the compressedrefrigerant flowing in the line 20 is directed into the condenser 12 butin the event that it is desired to defrost the evaporator 13, thecompressed refrigerant is allowed to flow directly into the evaporator18, in a manner to be described hereinafter. It will be noted that thecapillary tube restrictor 16 has its inlet end arranged in the receiver14 and has its outlet end terminating in a reciprocating valve-likemember 24 arranged at the inlet to the evaporator 18. The valvelikemember 24 normally seats against an apertured resilient bushing 26, asshown in FIGURE 2 of the drawing so as to prevent compressed refrigerantgas in the line 22 from entering the evaporator directly.

When the element 24 is seated against the element 26, the liquidrefrigerant leaving the outlet end of the capillary tub 16 is feddirectly into the evaporator 18.

When it is desired to defrost the evaporator 18, a solenoid coil 28 isenergized and this serves to pull the valve member 24 downwardly, asviewed in FIGURE 2, so as to unseat this member from the bushing 26. Themember 24 is of magnetic material and is provided with a plurality ofaxially extending grooves or fluid passages 27 in its outer peripherywhereby the high pressure refrigerant in the condenser is free to flowinto the evaporator whenever the solenoid 28 is energized.

When the element 24 is pulled away from the bushing 26, it is obviousthat both ends of the capillary tube will be subjected to substantiallythe same pressure with the result that little, if any, refrigerant flowwill take place in the capillary tube 16 and the main flow ofrefrigerant will be in the space between the capillary tube and theinner walls of the line 22 and through the passages 27. After theevaporator has been fully defrosted, the solenoid 28 will be deenergizedand when this takes place, the element 24 will reseat against thebushing 26. It will be noted that the outlet end of the capillary tubeis provided with a plurality of convolutions 30, which, in eifect, forma coil spring for biasing the member 24 into seating engagement with thebushing 26. A separate coil spring (not shown) could be provided, ifdesired, for biasing the element against the seat on the bushing 26.

For purposes of illustration, there is shown a control for the solenoid28 which operates in the following maner. During normal operation of theapparatus thus far described, the food in the food storage compartment40 is maintained at a temperature of approximately 36 F. for the purposeof preserving unfrozen foods. A thermostat 41 located on the evaporator18 normally cycles the motor compressor unit 10 through the switch 42 byopening the switch when the temperature at the thermostat 41 falls below18 F. and by reclosing the switch when the temperature at the thermostat41 exceeds 24 F.

Frost tends to accumulate on the evaporator 18 and the amount which doesaccumulate is determined to a large extent by the amount of produceplaced within the refrigerator and the frequency at which the doors tothe food compartment are opened. The above factors also determine to alarge extent the portion of the time during which the motor compressorunit 10 is required to operate and, consequently, the timer which hasbeen provided for timing the defrost cycle of the frozen foodcompartment is so connected in the circuit that it will only count thetime during which the motor compressor uni-t 10 operates. Thus, thetimer motor 50 includes a field winding 52 which is arranged as shown inseries with the switch 52 across the main power supply line 53. Thetimer motor 50 is provided with a driven cam 54 which serves to actuatea switch operating plunger 56, as shown. The plunger 56 is adapted toride on the cam 54 as shown and does not close any circuits until thecam follower 56 rides up onto the cam surface 58, at which time, acircuit is closed at the contacts 60. Closing of the circuit through thecontacts 60 short-circuits the thermostatic operated switch 42 wherebythe motor compressor unit 10 will serve to operate even though thetheromstat 41 may indicate that no refrigeration is required. Thepurpose of this is to build up the head pressure in the condenser 12just prior to the defrosting of the evaporator 18. The cam 54 isprovided with a second raised portion 62 which subsequently serves toraise the cam follower high enough to close the circuit through thecontacts 64. When the contacts 64 are closed, current is fed to thevalve controlling solenoid 28 so as to cause the element 24 to movedownwardly, as viewed in FIGURE 2. Upon energization of the solenoid 28and downward movement of the valve 24,

hot uncondensed refrigerant -vapor contained in the condenser and thelines connected to the outlet of the motor compressor unit is free toflow upwardly past the valve element 24 into the evaporator 18. Thecondensed liquid in the condenser 12 goes through a phase change becauseof the sudden lowering of the vapor pressure upon it. Thus, the liquidin the condenser boils and the condenser 12 becomes a high temperatureevaporator. The vapor in the condenser then passes up the line 22surrounding the restrictor 16 into the evaporator 18. The quantity ofvapor which is fed through the line 22 into the evaporator 18 fordefrost purposes is in excess of that actually required to defrost theevaporator whereby the refrigerant vapor which has been condensed in theevaporator 18 during the defrost cycles is reevaporated by such excessrefrigerant prior to its return to the compressor, with the results thatno slugs of refrigerant enter the compressor.

Insofar as certain aspects of this invention are concerned, other typesof control systems could be used for controlling the solenoid 28.Likewise, the refrigeration system can be used in a wide variety ofrefrigerators and only the simplest form of refrigerator has been shownfor purposes of illustrating the invention.

7 While the embodiment of the present invention as herein disclosedconstitutes a preferred form, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. In a refrigerating system, the combination, a compressor, acondenser, an evaporator, a receiver connected to the outlet of saidcondenser, means for connecting the outlet of said evaporator to theinlet of said compressor,'--means for directing hot compressedrefrigerant gas from-the outlet of said compressor to the inlet of saidcondenser, a first conduit supplying liquefied refrigerant from saidreceiver to the inlet of said evaporator, means including a secondconduit surrounding the outlet end of said first conduit for supplyinghot refrigerant gas from-said condenser to the inlet of said evaporator.

2. In a refrigerator, a cabinet having a food storage compartmenttherein, an evaporator in said compartment, a compressor, a condenser,refrigerant flow means connecting said evaporator in refrigerant flowrelationship Withsaid compressor and said condenser, said refrigerantflow means including conduit means for selectively connecting the outletof said compressor to the inlet of said condenser or to the inlet ofsaid evaporator, said refrigerant flow means including a capillary tubeconcentric with at least a portion of said conduit means for connectingsaid condenser to the inlet of said evaporator, said refrigerant fiowmeans including means for lay-passing said capillary tube when theoutlet of said compressor is connected to the inlet of said evaporator.

3. In a refrigerator, a cabinet having a food storage compartmenttherein, an evaporator in said compartment, a compressor, a condenser,refrigerant flow means connecting said evaporator in refrigerant flowrelationship with said compressor and said condenser, said refrigerantflow means including conduit means for selectively connecting the outletof said compressor to the inlet of said condenser or to the inlet ofsaid evaporator, said refrigerant flow means including a capillary tubeconcentric with at least a portion of said conduit means for connectingsaid condenser to the inlet of said evaporator, a valve port elementdisposed in said conduit means-adjacent the inlet to said evaporator andarranged to be engaged by the outlet end of said capillary tube so as toseal off said conduit means from said evaporator, and means for movingthe outlet end of said capillary tube out of engagement with said valveport element so as to permit flow of refrigerant from said conduit meansinto said evaporator.

4. In a refrigerator, a cabinet having a food storage compartmenttherein, an evaporator in said compartment, a compressor, a condenser,refrigerant flow means connecting said evaporator in refrigerant flowrelationship with said compressor and said condenser, said refrigerantflow means including conduit means for selectively connecting the outletof said compressor to the inlet of said condenser or to the inlet ofsaid evaporator, said refrigerant flow means including a capillary tubeconcentric with at least a portion of said conduit means for connectingsaid condenser to the inlet of said evaporator, a valve port elementdisposed in said conduit means adjacent the inlet to said evaporator andarranged to be engaged by the outlet end of said capillary tube so as toseal off said conduit means from said evaporator, means for moving theoutlet end of said capillary tube out of engagement with said valve portelement so as to permit flow of refrigerant from said conduit means intosaid evaporator, a solenoid coil adjacent said outlet end of saidcapillary tube, and an armature secured to said outlet end for actuatingsaid end in response to energization of said solenoid coil.

5. In a refrigerator, a cabinet having a food storage compartmenttherein, an evaporator in said compartment, a compressor, a condenser,refrigerant flow means connecting said evaporator in refrigerant flowrelationship with said compressor and said condenser, said refrigerantflow means including conduit means for selectively connecting the outletof said compressor to the inlet of said condenser or to the inlet ofsaid evaporator, said refrigerant flow means including a capillary tubeconcen- 9 trio with at least a portion of said conduit means forconnecting said condenser to the inlet of said evaporator, a valve portelement disposed in said conduit means adjacent the inlet to saidevaporator and arranged to be engaged by the outlet end of saidcapillary tube so as to seal off said conduit means from saidevaporator, means for moving the outlet end of said capillary tube outof engagement with said valve port element so as to permit flow ofrefrigerant from said conduit means into said evaporator, a solenoidcoil adjacent said outlet end of said capillary tube, and an armaturesecured to said outlet end for actuating said end in response toenergization of said solenoid coil, said armature having longitudinallyextending fluid passages formed therein through which refrigerant flowswhen said solenoid coil is energized.

6. In a refrigerator, a cabinet having a food storage compartmenttherein, an evaporator in said compartment, a compressor, a condenser,refrigerant flow means connecting said evaporator in refrigerant flowrelationship with said compressor and said condenser, said refrigerantflow means including conduit means for selectively connecting the outletof said compressor to the inlet of said condenser or to the inlet ofsaid evaporator, said refrigerant flow means including a capillary tubeconduit means for connecting said condenser to the inlet of saidevaporator, a valve port element disposed in said conduit means adjacentthe inlet to said evaporator and arranged to be engaged by the outletend of said capillary tube so as to seal off said conduit means fromsaid evaporator, means for moving the outlet end of said capillary tubeout of engagement with said valve port element so as to permit flow ofrefrigerant from said conduit means into said evaporator, a solenoidcoil adjacent said outlet end of said capillary tube, and an armaturesecured to said outlet end for actuating said end in response toenergization of said solenoid coil, said capillary tube comprising acoiled intermediate portion forming a spring means for biasing theoutlet end of said capillary tube into engagement with said valve port.

7. Refrigerating apparatus comprising in combination, a refrigerantcompressor, a condenser, an evaporator, a capillary tube type restrictorhaving its outlet end movable into and out of engagement with the inletto said evaporator, means for connecting said compressor, condenser,restrictor and evaporator in series refrigerant flow relationship, athermostatic cycling control means for starting and stopping theoperation of said compressor at relatively frequent intervals, means forsupplying compressed refrigerant to said evaporator at defrostingtemperatures so as to defrost said evaporator, and means for controllingthe supply of said compressed refrigerant to said evaporator so as tocause defrosting thereof at relatively less frequent intervals, saidlast named means comprising means for actuating the outlet end of saidcapillary tube into and out of engagement With the inlet of saidevaporator.

8. In a refrigerator, a cabinet having a food storage compartmenttherein, an evaporator in said compartment, a compressor, a condenser,refrigerant flow means conmeeting said evaporator in refrigerant flowrelationship with said compressor and said condenser, said refrigerantflow means including conduit means connecting the outlet of saidcompressor to the inlet of said condenser and to the inlet of saidevaporator, a capillary tube connecting the outlet of said condenser tothe inlet of said evaporator, said capillary tube having its outletterminating adjacent the inlet of said evaporator, the inlet to saidevaporator having a valve seat formed therein, said tube having amovable valve portion secured to its outlet end and cooperating withsaid seat to prevent the flow of refrigerant from said conduit meansinto said evaporator in one position of valve portion.

9. In a refrigerator, a cabinet having a food storage compartmenttherein, an evaporator in said compartment, a compressor, a condenser,refrigerant flow means connecting said evaporator in refrigerant flowrelationship with said compressor and said condenser, said refrigerantflow means including conduit means connecting the outlet of saidcompressor to the inlet of said condenser and to the inlet of saidevaporator, a capillary tube connecting the outlet of said condenser tothe inlet of said evaporator, said capillary tube having its outletterminating adjacent the inlet of said evaporator, the inlet to saidevaporator having a valve seat formed therein, said tube having amovable valve portion secured to its outlet end and cooperating withsaid seat to prevent the flow of refrigerant from said conduit meansinto said evaporator in one position of valve portion, and magneticmeans for actuating said movable valve portion.

10. Refrigerating apparatus comprising in combination, a refrigerantliquefying means including a condenser, an evaporator, a capillary tuberestrictor supplying refrigerant from said condenser to the inlet ofsaid evaporator, means for returning evaporated refrigerant from saidevaporator to said liquefying means, a thermostatic cycling controlmeans for starting and stopping the operation of said liquefying meansat relatively frequent intervals, and means for supplying compressedrefrigerant to said evaporator at defrosting temperatures so as todefrost said evaporator at less frequent intervals, and means forcontrolling the supply of said refrigerant to said evaporator includingmeans for moving a portion of said restrictor so as to control the flowof refrigerant to said evaporator.

11. Refrigerating apparatus comprising in combination, a refrigerantliquefying means including a condenser, and evaporator, a restrictortube supplying liquid refrigerant from said condenser to the inlet ofsaid evaporator, means for returning evaporated refrigerant from saidevaporator to said liquefying means, a thermostatic cycling means forstarting and stopping the operation of said liquefying means atrelatively frequent intervals, and control means for supplyingcompressed refrigerant to said evaporator at defrosting temperatures soas to defrost said evaporator at relatively infrequent nitervals, saidcontrol means having means for preventing the stopping of saidliquefying means immediately preceding the defrosting of saidevaporator, said means for controlling the supply of said compressedrefrigerant to said evaporator including means for moving the outlet ofsaid restrictor tube out of engagement with the inlet to saidevaporator.

12. In a refrigerator, a cabinet having a food storage compartmenttherein, an evaporator in said compartment, a compressor, a condenser,refrigerant flow means connecting said evaporator in refrigerant flowrelationship with said compressor and said condenser, said refrigerantflow means including first conduit means connecting the outlet of saidcompressor to the inlet of said condenser and to the inlet of saidevaporator, and a capillary restrictor concentric With at least aportion of said conduit means for supplying liquid refrigerant from saidcondenser to the inlet of said evaporator, said re strictor comprising acapillary tube terminating adjacent the inlet of said evaporator, theinlet to said evaporator having a valve seat formed therein, said tubehaving a movable valve portion cooperating with said seat to prevent theflow of refrigerant from said conduit means into said evaporator in oneposition of said valve portion.

References Cited in the file of this patent UNITED STATES PATENTS2,145,774 Mufily Jan. 31, 1939 2,785,542 Thomas Mar. 19, 1957 2,888,808Jacobs June 2, 1959 2,959,027 Ewing Nov. 8, 1960

